Relevance of erosion processes when modelling in-channel gravel debris flows for efficient hazard assessment

Gregoretti, Carlo; Stancanelli, Laura Maria; Bernard, Martino; Boreggio, Mauro; Degetto, Massimo; Lanzoni, Stefano

doi:10.1016/j.jhydrol.2018.10.001

Cited by 66 publications

(60 citation statements)

References 62 publications

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“…The employed GIS-based debris flows cell routing model is able to simulate the routing and the entrainment-deposition processes of solid-liquid mixtures having a grain-collision dominated rheology (Gregoretti et al, 2018a), also known as stony debris flows (Takahashi, 2007). It represents the fully bi-phase version of the one proposed by Gregoretti et al (2016a), and it allows a better simulation of the entrainment process.…”

Section: Gis-based Routing Cell Modelmentioning

confidence: 99%

“…From a numerical point of view, the governing equations are solved by using the finite difference technique with an explicit scheme subject to the Courant-Friedrichs-Lewy stability condition. The initial conditions are represented by the inflow solid-liquid hydrograph computed by means of a triggering model (e.g., Gregoretti et al, 2016bGregoretti et al, , 2018a. The computation procedure starts defining for each cell the possible solid-liquid discharges toward its eight surrounding ones according to Equations (3,4).…”

Section: Gis-based Routing Cell Modelmentioning

confidence: 99%

“…The hydraulic simulation of the Rovina di Cancia debris flow was carried out by using the cell routing model proposed by Gregoretti et al (2018a) and described in subsection GIS-based routing cell model.…”

Section: Evaluation Of the Effects Of The Gridding Techniques On Debrmentioning

confidence: 99%

“…Two event scenarios, corresponding respectively to 50-and 300-years return period, were defined by means of a coupled hydrological and triggering model (e.g., Gregoretti et al, 2016bGregoretti et al, , 2018a, starting from the rainfall depth-duration frequencies curves. It enabled to investigate the influence of the gridding methods on debris flows routing model results for events having different magnitude, characteristics of two usual design return periods.…”

Section: Evaluation Of the Effects Of The Gridding Techniques On Debrmentioning

confidence: 99%

“…Hazard mapping consists in identifying the areas that are threatened either historically or potentially by debris flows. The methods used to simulate potential hazard scenarios are both empirical-based (e.g., Scheidl and Rickenmann, 2010;Berti and Simoni, 2014) and model-based (e.g., Rickenmann et al, 2006;Deangeli, 2008;Medina et al, 2008;Armanini et al, 2009;Hussin et al, 2012;Gregoretti et al, 2018a). Since the topography is the major control over fluxes of water and sediments (Moore and Grayson, 1991;Hancock, 2006;Saksena and Merwade, 2015), the topographic data usually in the form of DEMs represent the most important input in debris flows routing models (e.g., Rickenmann et al, 2006;Sodnik et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Evaluating the Differences of Gridding Techniques for Digital Elevation Models Generation and Their Influence on the Modeling of Stony Debris Flows Routing: A Case Study From Rovina di Cancia Basin (North-Eastern Italian Alps)

2018

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Debris flows are among the most hazardous phenomena in mountain areas. To cope with debris flow hazard, it is common to delineate the risk-prone areas through routing models. The most important input to debris flow routing models are the topographic data, usually in the form of Digital Elevation Models (DEMs). The quality of DEMs depends on the accuracy, density, and spatial distribution of the sampled points; on the characteristics of the surface; and on the applied gridding methodology. Therefore, the choice of the interpolation method affects the realistic representation of the channel and fan morphology, and thus potentially the debris flow routing modeling outcomes. In this paper, we initially investigate the performance of common interpolation methods (i.e., linear triangulation, natural neighbor, nearest neighbor, Inverse Distance to a Power, ANUDEM, Radial Basis Functions, and ordinary kriging) in building DEMs with the complex topography of a debris flow channel located in the Venetian Dolomites (North-eastern Italian Alps), by using small footprint fullwaveform Light Detection And Ranging (LiDAR) data. The investigation is carried out through a combination of statistical analysis of vertical accuracy, algorithm robustness, and spatial clustering of vertical errors, and multi-criteria shape reliability assessment. After that, we examine the influence of the tested interpolation algorithms on the performance of a Geographic Information System (GIS)-based cell model for simulating stony debris flows routing. In detail, we investigate both the correlation between the DEMs heights uncertainty resulting from the gridding procedure and that on the corresponding simulated erosion/deposition depths, both the effect of interpolation algorithms on simulated areas, erosion and deposition volumes, solid-liquid discharges, and channel morphology after the event. The comparison among the tested interpolation methods highlights that the ANUDEM and ordinary kriging algorithms are not suitable for building DEMs with complex topography. Conversely, the linear triangulation, the natural neighbor algorithm, and the thin-plate spline plus tension Boreggio et al.Interpolation Influence on Routing Modeling and completely regularized spline functions ensure the best trade-off among accuracy and shape reliability. Anyway, the evaluation of the effects of gridding techniques on debris flow routing modeling reveals that the choice of the interpolation algorithm does not significantly affect the model outcomes.

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Section: Gis-based Routing Cell Modelmentioning

confidence: 99%

Section: Gis-based Routing Cell Modelmentioning

confidence: 99%

Section: Evaluation Of the Effects Of The Gridding Techniques On Debrmentioning

confidence: 99%

Section: Evaluation Of the Effects Of The Gridding Techniques On Debrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating the Differences of Gridding Techniques for Digital Elevation Models Generation and Their Influence on the Modeling of Stony Debris Flows Routing: A Case Study From Rovina di Cancia Basin (North-Eastern Italian Alps)

2018

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Grain‐energy release governs mobility of debris flow due to solid–liquid mass release

Cao

Borthwick

et al. 2020

Earth Surf Processes Landf

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Debris flows often exhibit high mobility, leading to extensive hazards far from their sources. Although it is known that debris flow mobility increases with initial volume, the underlying mechanism remains uncertain. Here, we reconstruct the mobility–volume relation for debris flows using a recent depth‐averaged two‐phase flow model without evoking a reduced friction coefficient, challenging currently prevailing friction‐reduction hypotheses. Physical experimental debris flows driven by solid–liquid mass release and extended numerical cases at both laboratory and field scales are resolved by the model. For the first time, we probe into the energetics of the debris flows and find that, whilst the energy balance holds and fine and coarse grains play distinct roles in debris flow energetics, the grains as a whole release energy to the liquid due to inter‐phase and inter‐grain size interactions, and this grain‐energy release correlates closely with mobility. Despite uncertainty arising from the model closures, our results provide insight into the fundamental mechanisms operating in debris flows. We propose that debris flow mobility is governed by grain‐energy release, thereby facilitating a bridge between mobility and internal energy transfer. The initial volume of debris flow is inadequate for characterizing debris flow mobility, and a friction‐reduction mechanism is not a prerequisite for the high mobility of debris flows. By contrast, inter‐phase and inter‐grain size interactions play primary roles and should be incorporated explicitly in debris flow models. Our findings are qualitatively encouraging and physically meaningful, providing implications not only for assessing future debris flow hazards and informing mitigation and adaptation strategies, but also for unravelling a spectrum of earth surface processes including heavily sediment‐laden floods, subaqueous debris flows and turbidity currents in rivers, reservoirs, estuaries, and ocean. © 2020 John Wiley & Sons, Ltd.

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Runoff‐generated debris flows: Observation of initiation conditions and erosion–deposition dynamics along the channel at Cancia (eastern Italian Alps)

Simoni

Bernard

Berti

et al. 2020

Earth Surf Processes Landf

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In the Dolomitic region, abundant coarse hillslope sediment is commonly found at the toe of rocky cliffs. Ephemeral channels originate where lower permeability bedrock surfaces concentrate surface runoff. Debris flows initiate along such channels following intense rainfall and determine the progressive erosion and deepening of the channels. Sediment recharge mechanisms include rock fall, dry ravel processes and channel-bank failures. Here we document debris flow activity that took place in an active debris flow basin during the year 2015. The Cancia basin is located on the southwestern slope of Mount Antelao (3264ma.s.l.) in the dolomitic region of the eastern Italian Alps. The 2.5km 2 basin is incised in dolomitic limestone rocks. The data consist of repeated topographic surveys, distributed rainfall measurements, time-lapse (2s) videos of two events and pore pressure measurements in the channel bed. During July and August 2015, two debris flow events occurred, following similarly intense rainstorms. We compared rainfall data to existing rainfall triggering thresholds and simulated the hydrological response of the headwater catchment with a distributed model in order to estimate the total and peak water discharge. Our data clearly illustrate how debris entrainment along the channel is the main contributor to the overall mobilized volume and that erosion is dominant when the channel slope exceeds 16°. Further downstream, sediment accumulation and depletion occurred alternately for the two successive events, indicating that sediment availability along the channel also influences the flow behaviour along the prevailing-transport reach. The comparison between monitoring data, topographical analysis and hydrological simulation allows the estimation of the average solid concentration of the two events and suggests that debris availability has a significant influence on the debris flow volume.

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Relevance of erosion processes when modelling in-channel gravel debris flows for efficient hazard assessment

Cited by 66 publications

References 62 publications

Evaluating the Differences of Gridding Techniques for Digital Elevation Models Generation and Their Influence on the Modeling of Stony Debris Flows Routing: A Case Study From Rovina di Cancia Basin (North-Eastern Italian Alps)

Evaluating the Differences of Gridding Techniques for Digital Elevation Models Generation and Their Influence on the Modeling of Stony Debris Flows Routing: A Case Study From Rovina di Cancia Basin (North-Eastern Italian Alps)

Grain‐energy release governs mobility of debris flow due to solid–liquid mass release

Runoff‐generated debris flows: Observation of initiation conditions and erosion–deposition dynamics along the channel at Cancia (eastern Italian Alps)

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